This little stand is the first I've seen of these. They're omelette style eggs and rice with a filling of sausage, or salmon, or seafood. Cooked fresh, and served with sweet radish, and sauce. They're like giant savoury Kanon Krok's, very yummy.
There's a smaller version of these balls made with octopus inside, a famous Japanese dish, tako-yaki you'll see in a lot of places in Bangkok.
I thought she joined the two halves together, but now I realize she just turned the half ball over, using all the extra mixture to form both halves and make a round ball.
Served with sweet radish and ketchup, but needs a good kick of chillies I think.
You can find the stand here, near the entrance to Jatujak: